CHICAGO — Several well-known Democratic supporters, including longtime allies of President Barack Obama, said Thursday that they're backing Republican venture capitalist Bruce Rauner for Illinois governor, signaling that the campaign will focus on swing voters crucial to winning in the heavily Democratic state.

Rauner spoke Thursday at a downtown Chicago hotel flanked by a group of more than 20 supporters he's billing as "Democrats and Independents for Rauner." He said his approach to solving the state's problems has nothing to do with political affiliation.

"Solving problems is not partisan, leadership is not partisan ... consensus building is not partisan," Rauner said.

Backers include longtime Obama supporter and former Federal Communications Commission Chairman Newton Minow, 88, who said he's taking "a leave of absence from my party" to support Rauner.

"Illinois is in desperate shape ... (and) I regard this as a decisive, important election," said Minow, a founder of the Chicago law firm Sidley Austin who gave Obama his first job after law school.

Minow said that in a Rauner administration, "there won't be a big difference between Democrats and Republicans because the problems are too tough and they've got to be solved."

Former Democratic National Finance Committee member Manny Sanchez, a Chicago attorney who led Latino outreach in Obama's two presidential campaigns but considers himself an independent, said two-thirds of Illinois voters probably are independents even if they normally vote with a specific party.

"I know Rauner is a centrist ... and represents the majority of Illinois," Sanchez said. "This is not the time to be bogged down in ideological support of parties."

Gov. Pat Quinn, a Chicago Democrat, has acknowledged it'll be a difficult re-election bid considering the millions that Rauner has raised and spent. But he told reporters Thursday that he wasn't worried about Rauner making inroads with Democrats.

Rauner narrowly won the four-way GOP primary over state Sen. Kirk Dillard.

"Looking at the results of the Republican primary, I think he has plenty of work to do on that side," Quinn said. "He didn't get resounding victory at all from his own party. There's always going to be people who pick a different candidate. I think we'll do very well with the Democratic Party."

Quinn has the support of labor unions, which spent millions on ads during the primary to attack Rauner. The GOP nominee has said he wants to curtail public unions, much like Wisconsin Gov. Scott Walker and former Indiana Gov. Mitch Daniels did.

But Republicans see Obama's home state — one of the Midwest's last Democratic strongholds - as one of their top two opportunities to pick up a governorship, largely because of Illinois' massive financial problems. On Wednesday the Republican Governors Association donated $750,000 to Rauner's campaign.

Rauner says that the support of longtime Democrats — including former state Sen. James Meeks, pastor of the Salem Baptist Church of Chicago — is emblematic of the bipartisan leadership approach he would take. He said members of both parties would have to see if there is a compromise to let a 67 percent income tax hike expire while making up the revenue, including by investigating if other states tax things that Illinois does not.

But, he said: "We need to grow ... we can't tax our way out of our problems."

Still, unions said they would work to keep Rauner from getting elected in November.

"His kind of divisive leadership is not welcome in Illinois," said Illinois AFL-CIO president Michael Carrigan in a statement this week. "We know that competing against his stacks of money will be difficult, but we continue ... what we started months ago - making sure the working families of Illinois understand the Rauner in his TV commercials is fiction."

Quinn has repeatedly said he inherited the state's fiscal mess five years ago, but has gotten it back on track, including with a capital construction bill and a bill to help address the state's worst-in-the-nation pension shortfall.